1. Field of the Invention
The present invention relates to a machining center, and more particularly, to a parallel mechanism for allowing a pentahedral machining by a single set-up, and for allowing a multi-machining including turning, boring, drilling, grinding as well as milling.
2. Description of the Related Art
It is necessary to control a three-dimensional position and orientation of a tool, in machining using a machining center, so as to shape and form raw materials into useful, desired products. A serial mechanism shown in FIG. 1, is the most fundamental mechanism, used for manipulating the position and orientation control. The serial mechanism has a construction which allows every shaft between a base 1000 and a spindle 1200 to be at right angles with one another. This mechanism has the advantages of a relatively large workspace, and a simplified operation software and controller.
In recent years, there has been made a study of a parallel mechanism capable of motion in six degrees of freedom, employed for a machining center. The parallel mechanism features a design that can connect a base and a spindle parallel with each other, by using a plurality of links.
FIG. 2 shows a typical parallel mechanism, explaining a hexapod structure which allows connecting a base 2100 and a spindle 2200 by means of six links. These links are expanded to be capable of motion in six degrees of freedom.
In general, the machining center with the hexapod structure is divided into two kinds according to a position of the spindle: vertical machining center and horizontal machining center. The former is to machine only a vertical plane of a workpiece. The latter is to machine only a horizontal plane of a workpiece. Therefore, a machining for both vertical and horizontal planes of a workpiece isn't achieved by a single machining center. In addition, a turning process is impossible by the machining center with the typical parallel mechanism, requiring an additional process on a lathe.